JPS59109538A - Radial-ply tire - Google Patents

Abstract

PURPOSE:To provide a steel radial-ply tire which has excellent durability and in which belt separation is prevented, by using a rubber compsn. obtd. by blending sulfur, a cobalt salt and a specified carbon black with a raw rubber, as belt rubber for the radial-ply tire. CONSTITUTION:Hard carbon black contg. at least 70wt% carbon black having an iodine adsorption of 100-140mg/g and a dibutyl phthalate oil adsorption of 70-130ml/100g is used. A rubber compsn. consisting of 100pts.wt. raw rubber (contg. at least 90wt% natural rubber and/or polyisoprene rubber), 3.2-8pts.wt. sulfur, 0.05-0.8pts.wt. (in terms of cobalt) cobalt naphthenate, cobalt rosinate or cobalt linear C5-C20 monocarboxylate (e.g., cobalt stearate) and 45-80pts.wt. said carbon black is used as belt rubber for radial-ply tire.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radial tire, more specifically, the main rubber is natural rubber and/or polyisoprene rubber, and sulfur, cobal l-salt of an organic acid, and carbon black are blended in a specific range, In addition, by selecting a hard carbon black having specific properties as the majority of the carbon black to be blended, and further blending meta-cresol resin as desired, the rubber composition is used as belt rubber for radial tires. Edge separation, Bell 1 - Relates to a radial tire with significantly improved separation.

In recent years, there has been an extremely high demand for safety, high-speed running performance, durability, etc. of the A7 automobile tie. For this reason, high quality is now required to prevent destruction of tire separation and the like. Breakage of this separation, etc. often occurs from around the reinforcing layer, such as the bell 1 or carcass. Bell 1 separation, which is often seen in steel tires, is often developed from bell 1 edge separation to belt separation. In order to prevent this separation from breaking, many steel tires with highly durable steel belts have been manufactured. Further, in order to prevent destruction of the belt separation, etc., steel cord-coated rubber is also being considered.

From this point of view, the present inventors investigated the physical properties of steel tire belt separation and coating rubber, but found that it is difficult to fundamentally eliminate separation with the conventionally used steel cord coating rubber. Therefore, the present inventors created a rubber composition containing a large amount of sulfur and a salt of Kobal 1, an organic acid, and used carbon black HAF-LS (loin) as carbon black.
The application was filed for a rubber composition containing meta-cresol resin and a small amount of a vulcanization accelerator.

However, even with this rubber composition, prevention of destruction such as separation was not always sufficient.

The present invention aims to significantly improve the belt-resistant separation of tires, and is particularly suitable for use in steel radial tires.

In accordance with this objective, the present inventors conducted research on improving the belt separation resistance of steel tires and found that belt separation depends on the properties of the carbon black blended into the rubber composition used for the steel cord coating rubber. I found out.

For steel cord coated rubber, adhesion between the steel cord and the rubber is important. For this reason, the rubber composition used for steel cord coated rubber has a compounding agent for adhesion, such as H
RH (hexamethylene 1-lamine, resorcinol, hysil) and cobalt salts of organic acids are added. In addition, sulfur and the like are also involved in adhesion to steel cords, but are often blended in relatively large amounts. In consideration of adhesion to the steel coat, many studies have been made on the above-mentioned adhesion compounding agents for rubber compositions used for steel cord coated rubber. However, it has been found that belt edge separation and belt separation are largely influenced by not only the steel adhesion but also the physical properties of the steel cord-coated rubber. That is, properties such as (1) high hardness, (2) high physical properties at break (high tensile strength, high elongation at break), (2) good aging physical properties, and (2) low flex cracking property (crack growth property) are required. Conventionally, in the rubber composition of steel cord coating rubber, soft carbon black is considered to have relatively good adhesion to the steel coat, so hard carbon black is not used.
Even the hardest carbon black is carbon black)
It was common to use a grade of about IAF.

However, as a result of research to improve belt separation, we found that carbon black HA and F have even harder iodine adsorption @ffl 100-140ml/1ll/
Q1 dibutyl phthalate q & oil 1170~130ttl
The inventors have discovered that by using carbon black in the range of /100Q, such as carbon black 15AF, tire belt separation control does not occur, and the present invention has been achieved.

Carbon black l5The hard carbon black on AFLI has traditionally been used in rubber compositions for parts that come into contact with the road surface and wear, such as cap treads, and is used in rubber compositions for parts such as cap treads that come into contact with the road surface and wear, and for internal rubber compositions such as steel cord coated rubber. It was difficult to cover the composition. The present inventors studied the relationship between belt separation and the rubber composition of the steel cord coating rubber and discovered the effect of hard carbon black.

That is, the present invention comprises 90% by weight of natural rubber and/or polyisoprene rubber.
3.2 parts by weight of sulfur per 100 parts by weight of raw rubber containing the above
~8 parts by weight, cobalt naphthenate, cobalt rosin acid, or a cobalt salt of a linear or branched monocarboxylic acid having 5 to 20 carbon atoms, with a cobalt element content of 0.05
~0.8 parts by weight ω and 45 to 80 parts by weight of carbon black, and 10% by weight or more of the carbon black formulation has an iodine adsorption amount of 100 to 140 mQ/Q and a dibutyl phthalate (DBP) oil absorption m of 70 to 130ffi/
A radial tire characterized by using a rubber composition of 100 (+ carbon black) for belt rubber.

The steel cord coated rubber used in the present invention preferably has the following composition except for the carbon black grade. That is, it is preferable to incorporate a large amount of sulfur m. Steel cords used in steel tires usually have a positive plating applied to the surface, and it is known that this positive copper reacts with the sulfur in the rubber to form an adhesive. If carbon black 15AF or more hard carbon black is used, the adhesion will be somewhat poor, so it is better to add more sulfur to the rubber. Cobalt salts of organic acids, commonly used as adhesion aids, are also required.

In other words, a rubber composition containing a large amount of sulfur and a cobalt salt of an organic acid and a hard carbon black of carbon black 15AF or higher is effective.

The raw rubber used for the steel cord coating rubber in the radial tire of the present invention is preferably natural rubber, polyisoprene rubber, or a mixture thereof, but 10 parts by weight or less of 100 parts by weight of the raw rubber is mixed with styrene-butadiene. It can also be replaced with other rubbers such as polymer rubber (SBR) and polybutadiene rubber (BR) W.

The amount of sulfur used in the steel cord coating rubber of the present invention is preferably 3.2 to 8.0 parts by weight, preferably 4.0 to 6.4 parts by weight, based on 100 parts by weight of the raw rubber.

If the amount is less than 3.2 parts by weight, adhesion will not be sufficient;
If more than 0 parts by weight is added, not only will physical properties such as elongation at break be greatly reduced, but sulfur will tend to bloom on the unvulcanized surface, especially on the rubber surface, which will be disadvantageous in processing. In addition, as the sulfur to be used, it is preferable to use insoluble sulfur from the viewpoint of preventing the occurrence of bloom. In the case of 4 to 10 parts by weight.

In addition, in the present invention, the organic acid cobal]-salt used in the steel cord coating rubber is cobalt naphthenate, cobalt rosinate [- or cobalt stearate, cobalt oleate, etc., which has a linear or branched carbon number of 5 to 20. Cobalt salts of monocarboxylic acids or “Manobond”
A cobalt salt of an organic acid containing boron such as (trade name, manufactured by MAM Chem 0), preferably 0.1 to 0.8 parts by weight of cobalt element per 100 parts by weight of raw rubber.
．． It is 2 to 0.5 parts by weight.

The amount of carbon black in the steel cord coated rubber used in the present invention is 45 to 8 parts by weight per 100 parts by weight of raw rubber.
0 heavy parts, iodine adsorption amount of 10% by weight or more of the total carbon black, 1oo~14oIIIg/g, D B
P Oil absorption 170-130rj/100g ft5 [l
11(7) It is necessary to contain hard carbon black of 15AF class. Such carbon blacks are N-219 and N- according to the ASTM designation.
220, N-231, N-242, etc. are exemplified.

Furthermore, as mentioned above, when a large amount of carbon black (15AF class) is used in the steel cord coating rubber, the adhesion to the steel cord tends to decrease slightly, but it can be brought to a good level by adding metacresol resin. The metacresol resin mentioned here is a product obtained by reacting metacresol with formalin or parabomaldehyde under an acid catalyst, and metacresol alone has 3 to 6 nuclei, such as Sumikanol 610, a product of Sumitomo Chemical. The metacresol resin is preferably blended in an amount of 1 to 10 parts by weight, more preferably 3 to 7 parts by weight, based on 100 parts by weight of the raw rubber.

In the steel cord coated rubber composition of the present invention, in addition to the above-mentioned compounding agents, commonly used compounding agents such as zinc oxide, stearic acid, anti-aging agents, vulcanization accelerators, etc. are blended in appropriate amounts.

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples. Note that all formulation values in Table 1 are parts by weight.

Flow Sides 1 to 8 and Comparative Examples 1 to 6 Rubber compositions were prepared by mixing raw rubber and compounding agents in the formulations shown in Table 1 using an ordinary Burberry mixer. The vulcanization properties and adhesion of this rubber composition were measured under the conditions and measurement methods shown below.

The results are shown in Table 1.

<Measurement of physical properties of rubber composition> Measurement of vulcanized physical properties is performed by forming a rubber composition into a sheet, vulcanizing it under predetermined vulcanization conditions to create a sheet, punching a JIS No. 3 dumbbell, and measuring the hardness (JIS, A). The elongation at break and tensile strength in the tensile test were measured according to JIS-K 6301-Section 3. Also, the aging test was carried out in a gear oven for 10
After being left at 0° C. for 24 hours, evaluation was made in the same manner as above. In addition, the bending fatigue test is based on the crack growth test in JIS-6.
According to Section 301-15 (bending test), 80℃, strain 20m
The length of growth was measured when the film was bent 100,000 times.

Also, the adhesion to steel cord is 1×5 (0,25
) using a plus plated steel cord
Perform a pull-out test according to MD-2229,
It is expressed as the pull-out force and rubber coverage (%) at that time. Adhesion evaluation was performed by proper vulcanization (160℃ x 20'), overvulcanization (160℃
x 60') and after proper vulcanization, it was pulled out in steam at 0° C. and 96% relative humidity for one week, and the water-resistant adhesion M was evaluated.

*7 Cobalt naphthenate, cobalt content 10% by weight
*8 Cobalt octylate, cobalt content 10 weight ratio *90 Cobalt dinate, cobalt content 10 weight ratio *10 Sulfur, insoluble sulfur 80% content *1
1 Vulcanization accelerator, NN dicyclohexylbenzothiazyl sulfenamide In Example 1 and Comparative Examples 1 to 6, a certain amount of cobalt salt of an organic acid was blended and the type of carbon black was changed for comparison. Carbon black GPF and carbon black FE with extremely low iodine adsorption amount as in Comparative Examples 1 and 2
In case of F, the adhesion to the steel cord was good, but the vulcanized physical properties were poor. In particular, the tensile strength and elongation at break show low values. As shown in Comparative Examples 3 to 6, the grade of carbon black HAF, which has a somewhat higher iodine adsorption amount, is better than Comparative Examples 1 to 2 using carbon black GPF or carbon black FEF, but Example 1 described below is better. -8 is inferior in tensile strength, elongation at break, and crack growth. On the other hand, in Examples 1 to 8 in which carbon black of carbon black 15AF grade was used, physical properties at break such as tensile strength and elongation at break were good.

In particular, the fracture properties after aging treatment are good, and the crack growth properties are also good.

On the other hand, in Examples 1 to 8 in which carbon black of carbon black l5AF grade was used, the adhesion to steel cord was slightly inferior in adhesion after proper vulcanization and water resistance, but it was improved to a good level by adding metacresol resin. (Comparison of Example 1 and Example 7, and Example 4 and Example 5).

Examples 9 to 13 and Comparative Examples 7 to 10 Eight rubber compositions of Comparative Examples 2 to 5 and Examples 1.4 to 5.7 to 8 were applied to passenger car steel radial tires size 1.
The rubber composition of Comparative Example 3 is the length of edge separation after running 50,000 km (the length of the separation that has progressed from the edge of Bell 1). The length of the tire using the tire (Comparative Example 8) was expressed as an index with 100 as the length. The results are shown in Table 2.

Table 2 As shown in Table 2, Examples 9 to 13 using carbon black with high iodine absorption level l5AF grade were significantly better than Comparative Examples 7 to 10 using other carbon blacks. One? It can be seen that there is an effect of improving separation.

Particularly in Examples 12 to 13, in which rubber compositions containing meta-cresol resin were used, the G drop was particularly noticeable.

As explained above, the main rubber is natural rubber and/or polyisoprene rubber, and sulfur,
Pal] ~ Blends salt and carbon black in a specific range,
In the present invention, a rubber composition in which a hard carbon black having specific properties is selected as most of the carbon black to be blended, and a meta-cresol resin is further blended as desired, is used as the bell 1 rubber of the radial tie A7. Radial tires are suitable for use as steel radial tires for passenger cars and the like because they have excellent bell t-valley resistance.

Patent applicant Yokohama Rubber Co., Ltd. Agent
Patent Attorney Tatsuo Ito Agent Patent Attorney Tetsuya Ito

Claims (1)

[Scope of Claims] 1. For 100 parts by weight of raw rubber containing 90% by weight or more of natural rubber and/or polyisoprene rubber,
．． 2 to 8 parts by weight, cobalt naphthenate, cobalt rosin acid 1 to 1, or a cobalt salt of a linear or branched monocarboxylic acid having 5 to 20 carbon atoms with a cobalt element content of 0.0
5 to 0.8 parts by weight and 45 to 80 parts by weight of carbon black, and 70% by weight or more of the carbon black blend has an iodine adsorption amount of 100 to 140 m! A radial tire characterized in that a rubber composition of carbon black with a dibutyl phthalate oil absorption of 70 to 130 yen/100 (1) is used for belt rubber.